<title> 信使</title><link href="http://hzoi.com/tomorrow.css" rel="stylesheet"><div class="ui existing segment"><pre><code><span class="pl-cp">#include</span><span class="pl-cpf">&lt;cstdio&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#include</span><span class="pl-cpf">&lt;cstring&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#include</span><span class="pl-cpf">&lt;queue&gt;</span><span class="pl-cp"></span>
<span class="pl-cp">#define w first</span>
<span class="pl-cp">#define node second</span>
<span class="pl-cp">#define MAXN 2005</span>
<span class="pl-cp">#define MAXM 4020024</span>
<span class="pl-cp">#define INF 0x7fffffff</span>
<span class="pl-cp">#define P pair&lt;double,int&gt;</span>
<span class="pl-k">using</span> <span class="pl-k">namespace</span> <span class="pl-n">std</span><span class="pl-p">;</span>
<span class="pl-k">struct</span> <span class="pl-n">Edge</span><span class="pl-p">{</span>
    <span class="pl-kt">int</span> <span class="pl-n">to</span><span class="pl-p">;</span>
    <span class="pl-kt">int</span> <span class="pl-n">w</span><span class="pl-p">;</span>
    <span class="pl-kt">int</span> <span class="pl-n">next</span><span class="pl-p">;</span>
    <span class="pl-n">Edge</span><span class="pl-p">(){</span><span class="pl-n">to</span><span class="pl-o">=</span><span class="pl-n">w</span><span class="pl-o">=</span><span class="pl-n">next</span><span class="pl-o">=</span><span class="pl-mi">0</span><span class="pl-p">;}</span>
<span class="pl-p">}</span> <span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">MAXM</span><span class="pl-p">];</span>
<span class="pl-kt">int</span> <span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">MAXM</span><span class="pl-p">];</span>
<span class="pl-kt">int</span> <span class="pl-n">si</span><span class="pl-p">;</span>

<span class="pl-kt">int</span> <span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">MAXN</span><span class="pl-p">];</span>
<span class="pl-kt">bool</span> <span class="pl-n">vis</span><span class="pl-p">[</span><span class="pl-n">MAXN</span><span class="pl-p">];</span>
<span class="pl-kt">int</span> <span class="pl-nf">main</span><span class="pl-p">(){</span>
    <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">0</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;</span><span class="pl-n">MAXN</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">)</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">INF</span><span class="pl-p">,</span><span class="pl-n">vis</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-nb">false</span><span class="pl-p">;</span>
    <span class="pl-kt">int</span> <span class="pl-n">n</span><span class="pl-p">,</span><span class="pl-n">m</span><span class="pl-p">;</span>
    <span class="pl-n">scanf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d%d&quot;</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">n</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">m</span><span class="pl-p">);</span>
    <span class="pl-kt">int</span> <span class="pl-n">x</span><span class="pl-p">,</span><span class="pl-n">y</span><span class="pl-p">,</span><span class="pl-n">z</span><span class="pl-p">;</span>
    <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;=</span><span class="pl-n">m</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">){</span>
        <span class="pl-n">scanf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d%d%d&quot;</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">x</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">y</span><span class="pl-p">,</span><span class="pl-o">&amp;</span><span class="pl-n">z</span><span class="pl-p">);</span>
        <span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-o">++</span><span class="pl-n">si</span><span class="pl-p">].</span><span class="pl-n">next</span><span class="pl-o">=</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">];</span>
        <span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">si</span><span class="pl-p">].</span><span class="pl-n">to</span><span class="pl-o">=</span><span class="pl-n">y</span><span class="pl-p">;</span>
        <span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">si</span><span class="pl-p">].</span><span class="pl-n">w</span><span class="pl-o">=</span><span class="pl-n">z</span><span class="pl-p">;</span>
        <span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">si</span><span class="pl-p">;</span>

        <span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-o">++</span><span class="pl-n">si</span><span class="pl-p">].</span><span class="pl-n">next</span><span class="pl-o">=</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">y</span><span class="pl-p">];</span>
        <span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">si</span><span class="pl-p">].</span><span class="pl-n">to</span><span class="pl-o">=</span><span class="pl-n">x</span><span class="pl-p">;</span>
        <span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">si</span><span class="pl-p">].</span><span class="pl-n">w</span><span class="pl-o">=</span><span class="pl-n">z</span><span class="pl-p">;</span>
        <span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">y</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">si</span><span class="pl-p">;</span>
    <span class="pl-p">}</span>
    <span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-mi">1</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-mi">0</span><span class="pl-p">;</span>
    <span class="pl-n">priority_queue</span><span class="pl-o">&lt;</span><span class="pl-n">P</span><span class="pl-p">,</span><span class="pl-n">vector</span><span class="pl-o">&lt;</span><span class="pl-n">P</span> <span class="pl-o">&gt;</span><span class="pl-p">,</span><span class="pl-n">greater</span><span class="pl-o">&lt;</span><span class="pl-n">P</span> <span class="pl-o">&gt;</span> <span class="pl-o">&gt;</span> <span class="pl-n">q</span><span class="pl-p">;</span>
    <span class="pl-n">q</span><span class="pl-p">.</span><span class="pl-n">push</span><span class="pl-p">(</span><span class="pl-n">make_pair</span><span class="pl-p">(</span><span class="pl-mi">0</span><span class="pl-p">,</span><span class="pl-mi">1</span><span class="pl-p">));</span>
    <span class="pl-k">while</span><span class="pl-p">(</span><span class="pl-o">!</span><span class="pl-n">q</span><span class="pl-p">.</span><span class="pl-n">empty</span><span class="pl-p">()){</span>
        <span class="pl-n">P</span> <span class="pl-n">now</span><span class="pl-o">=</span><span class="pl-n">q</span><span class="pl-p">.</span><span class="pl-n">top</span><span class="pl-p">();</span>
        <span class="pl-n">q</span><span class="pl-p">.</span><span class="pl-n">pop</span><span class="pl-p">();</span>
        <span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">vis</span><span class="pl-p">[</span><span class="pl-n">now</span><span class="pl-p">.</span><span class="pl-n">node</span><span class="pl-p">])</span><span class="pl-k">continue</span><span class="pl-p">;</span>
        <span class="pl-n">vis</span><span class="pl-p">[</span><span class="pl-n">now</span><span class="pl-p">.</span><span class="pl-n">node</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-nb">true</span><span class="pl-p">;</span>
        <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">x</span><span class="pl-o">=</span><span class="pl-n">head</span><span class="pl-p">[</span><span class="pl-n">now</span><span class="pl-p">.</span><span class="pl-n">node</span><span class="pl-p">];</span><span class="pl-n">x</span><span class="pl-p">;</span><span class="pl-n">x</span><span class="pl-o">=</span><span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">].</span><span class="pl-n">next</span><span class="pl-p">){</span>
            <span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">now</span><span class="pl-p">.</span><span class="pl-n">node</span><span class="pl-p">]</span><span class="pl-o">+</span><span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">].</span><span class="pl-n">w</span><span class="pl-o">&lt;</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">].</span><span class="pl-n">to</span><span class="pl-p">]</span> <span class="pl-o">||</span> <span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">].</span><span class="pl-n">to</span><span class="pl-p">]</span><span class="pl-o">==</span><span class="pl-n">INF</span><span class="pl-p">){</span>
                <span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">].</span><span class="pl-n">to</span><span class="pl-p">]</span><span class="pl-o">=</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">now</span><span class="pl-p">.</span><span class="pl-n">node</span><span class="pl-p">]</span><span class="pl-o">+</span><span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">].</span><span class="pl-n">w</span><span class="pl-p">;</span>
                <span class="pl-n">q</span><span class="pl-p">.</span><span class="pl-n">push</span><span class="pl-p">(</span><span class="pl-n">make_pair</span><span class="pl-p">(</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">].</span><span class="pl-n">to</span><span class="pl-p">],</span><span class="pl-n">edge</span><span class="pl-p">[</span><span class="pl-n">x</span><span class="pl-p">].</span><span class="pl-n">to</span><span class="pl-p">));</span>
            <span class="pl-p">}</span>
        <span class="pl-p">}</span>
    <span class="pl-p">}</span>
    <span class="pl-kt">int</span> <span class="pl-n">mi</span><span class="pl-o">=-</span><span class="pl-mi">1</span><span class="pl-p">;</span>
    <span class="pl-k">for</span><span class="pl-p">(</span><span class="pl-kt">int</span> <span class="pl-n">i</span><span class="pl-o">=</span><span class="pl-mi">1</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">&lt;=</span><span class="pl-n">n</span><span class="pl-p">;</span><span class="pl-n">i</span><span class="pl-o">++</span><span class="pl-p">){</span>
        <span class="pl-k">if</span><span class="pl-p">(</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">]</span><span class="pl-o">!=</span><span class="pl-n">INF</span><span class="pl-p">)</span><span class="pl-n">mi</span><span class="pl-o">=</span><span class="pl-n">max</span><span class="pl-p">(</span><span class="pl-n">mi</span><span class="pl-p">,</span><span class="pl-n">dis</span><span class="pl-p">[</span><span class="pl-n">i</span><span class="pl-p">]);</span>
    <span class="pl-p">}</span>
    <span class="pl-n">printf</span><span class="pl-p">(</span><span class="pl-s">&quot;%d</span><span class="pl-se">\n</span><span class="pl-s">&quot;</span><span class="pl-p">,</span><span class="pl-n">mi</span><span class="pl-p">);</span>
<span class="pl-p">}</span>
</cpde></pre></div>